An inverter, which performs the variable speed control of a motor such as an AC motor, is known as a motor drive device. Such a motor drive device can adjust the setting contents of various setting items. The motor drive device changes operating characteristics or obtains consistency with an external device by the adjustment of the setting contents.
First, the change of the operating characteristics will be described. The change of the rotational speed of a motor will be described as a specific example of the change of the operating characteristics. A motor drive device is connected to an external device. The external device is an external console panel, a host controller, or a signal transmitter. A setting signal is output from the external device. The setting signal is an analog voltage signal, an analog current signal, a pulse signal, or a signal similar thereto. When the setting signal is input to the motor drive device, the motor drive device sets the rotational speed. The change of the operating characteristics is performed in this way.
Subsequently, the consistency with an external device will be described. The motor drive device performs the adjustment (scaling) of a relationship between a setting signal to be input and an internal command value of the motor drive device according to use or the combination with the external device. The motor drive device includes an adjuster for adjusting a conversion factor such as a gain or an offset of an analog input. For example, a DC voltage signal in the range of +1 V to +5 V, which is applied from the outside to an input terminal to which a voltage of full scale in the range of 0 V to +10 V can be input, can be adjusted so as to be regarded in the range of 0% to 100% of an internal command. +1 V corresponds to an offset. Further, when a % is set, a gain can be set by computation. For example, when 50% is set, a gain is 3 V. The consistency with an external device is obtained in this way.
Further, for example, an invention disclosed in PTL 1 (JP-A-07-177759, title of the invention “INVERTER OPERATING DEVICE”) is known as the related art that performs setting of a motor drive device.
In this inverter operating device, information affecting the operation of an inverter is selected and displayed on a display. Specifically, when an operation for increasing a set value is performed by an increase key of the inverter operating device, the inverter operating device simultaneously displays three values, that is, the current value of the set value, a changed value after the operation, and the maximum allowable value of the set value. Accordingly, the operation of the inverter becomes easy and accurate.
Further, for example, an invention disclosed in PTL 2 (JP-A-03-52590, title of the invention “FUNCTION SETTING METHOD FOR INVERTER BY TWO-DIMENSIONAL GRAPH”) is known as another related art.
In this function setting method, a 7-Segment light-emitting diode (LED) and a liquid-crystal display (LCD) are used together with each other. The 7-Segment light-emitting diode (LED) displays a code number of a function to be set. The liquid-crystal display (LCD) displays a two-dimensional graph, which shows the contents of the function to be set corresponding to the code number, and the setting data thereof. Accordingly, it is possible to reduce the risk of erroneous function setting and the time that is required for setting.